Internal combustion engine valvetrain

ABSTRACT

An internal combustion engine valvetrain for an internal combustion engine. The internal combustion engine Includes one or more cylinders with one or more intake valves, one or more blowdown exhaust valves, and one or more scavenge exhaust valves. In one example, the internal combustion engine valvetrain includes a first valve actuation mechanism to open and close the blowdown exhaust valves, and Includes a second valve actuation mechanism to open and close the scavenge exhaust valves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/515,089 filed Aug. 4, 2011.

TECHNICAL FIELD

The technical field generally relates to internal combustion engine valvetrains.

BACKGROUND

Automotive internal combustion engines are often equipped with breathing systems to decrease emissions and increase engine efficiency. The breathing systems may include one or more turbochargers, one or more exhaust gas recirculation (EGR) assemblies, and other components. The internal combustion engines themselves commonly include intake and exhaust valves that are opened and closed by valvetrains. The exhaust gas exiting the internal combustion engines can in some cases be sent to the turbochargers, to the EGR assemblies, or to both.

SUMMARY OF ILLUSTRATIVE EMBODIMENTS

One illustrative embodiment includes an internal combustion engine valvetrain for an internal combustion engine. The internal combustion engine may have one or more cylinders. The cylinders may have one or more intake valves, one or more blowdown exhaust valves, and one or more scavenge exhaust valves. The internal combustion engine valvetrain may include a first valve actuation mechanism that is constructed and arranged to actuate the blowdown exhaust valves. The internal combustion engine valvetrain may include a second valve actuation mechanism that is constructed and arranged to actuate the scavenge exhaust valves. The first valve actuation mechanism may be a separate and distinct component than the second valve actuation mechanism.

One illustrative embodiment includes an internal combustion engine valvetrain for an internal combustion engine. The internal combustion engine may have one or more cylinders. The cylinders may have one or more intake valves, one or more blowdown exhaust valves, and one or more scavenge exhaust valves. The internal combustion engine valvetrain may include a first actuation means that may be constructed and arranged to actuate the blowdown exhaust valves and that may be constructed and arranged to actuate the intake valves. The internal combustion engine valvetrain may include a second actuation means that may be constructed and arranged to actuate the scavenge exhaust valve.

One illustrative embodiment includes a method which may include actuating a blowdown exhaust valve of an internal combustion engine. The method may also include separately and distinctly actuating a scavenge exhaust valve of the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic of an embodiment of an internal combustion engine.

FIG. 2 is a schematic of an embodiment of an internal combustion engine valvetrain.

FIG. 3 is a schematic of an embodiment of an internal combustion engine valvetrain.

FIG. 4 is a schematic of an embodiment of an internal combustion engine valvetrain.

FIG. 5 is a schematic of an embodiment of an internal combustion engine valvetrain.

FIG. 6 is a schematic of an embodiment of an internal combustion engine valvetrain.

FIG. 7 is a schematic of an embodiment of a variable valve timing mechanism.

FIG. 8 is a flow chart of an embodiment of a method of controlling exhaust gas flow divided between at least one turbocharger and at least one exhaust gas recirculation path.

FIG. 9 is a diagram of an embodiment of blowdown and scavenging exhaust valve timing at low engine speed and load.

FIG. 10 is a diagram of an embodiment of blowdown and scavenging exhaust valve timing for high turbocharger boost demand.

FIG. 11 is a diagram of an embodiment of blowdown and scavenging exhaust valve timing for variable turbocharger boost demand at intermediate engine speed and load.

FIG. 12 is a diagram of an embodiment of blowdown and scavenging exhaust valve timing for increased or sudden turbocharger boost demand at intermediate engine speed and load.

FIG. 13 is a diagram of another embodiment of blowdown and scavenging exhaust valve timing for increased or sudden turbocharger boost demand at intermediate engine speed and load.

FIG. 14 is a diagram of an embodiment of blowdown and scavenging exhaust valve timing for variable turbocharger boost demand at high engine speed and load.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following description of the embodiment(s) is merely illustrative in nature and is in no way intended to limit the invention, its application, or its uses.

The figures illustrate numerous embodiments of an internal combustion engine valvetrain 10 that may be equipped in an internal combustion engine 12 constructed and designed for divided exhaust gas flow—that is, blowdown and scavenge exhaust gas flow. In at least some of the embodiments, the internal combustion engine valvetrain 10 may provide independent control over the actuation of intake valves 14, blowdown exhaust valves 16, scavenge exhaust valves 18, or a combination thereof. In some cases, providing independent control over the actuation of the different valves 14, 16, 18 of the internal combustion engine 12 facilitates optimization of engine operation including, for example, increasing engine power and improving engine efficiency.

Referring to FIG. 1, the internal combustion engine (ICE) 12 may combust fuel with an oxidizer (e.g., air) and may expel fluid, such as exhaust gas which may include gas, liquid, and other matter, thereafter to an ICE breathing system (not shown). The ICE 12 may be a spark-ignited engine (e.g., gasoline, methanol), a diesel engine, an alternative fuel engine, or another type. The ICE 12 may be of different types having different arrangements and different numbers of cylinders (i.e., in-line, I-2, I-4, I-6, V-type, V-6, V-8, etc.). A cylinder block may sit below a cylinder head and may have cylindrical bores that accommodate reciprocating pistons. The ICE 12 may function under a four-stroke engine operating cycle with what-is-called a divided exhaust gas flow having a blowdown exhaust phase and a scavenging exhaust phase. In the blowdown exhaust phase, the blowdown exhaust valves 16 may open just before the associated piston reaches a bottom dead center (BDC) position. Exhaust gas then enters blowdown exhaust ports 20 under relatively increased pressure. In the scavenging exhaust phase, the scavenge exhaust valves 18 may open as the associated piston sweeps back up from the BDC position and toward a top dead center (TDC) position to displace most, if not all, of the remaining exhaust gas. The remaining exhaust gas then enters scavenge exhaust ports 22 under a comparatively decreased pressure. In some embodiments, an intake manifold, exhaust manifold, or both, may be provided for the ICE 12; the exhaust manifold may include a blowdown exhaust manifold and a scavenge exhaust manifold, which may be provided as separate components or as a one-piece component.

In the embodiment of FIG. 1, the ICE 12 may include a cylinder head 24 which, in the example shown, may include four cylinders 26 arranged in-line. Each cylinder 26 may have a pair of the intake valves 14 that communicate with an intake port 28, a single blowdown exhaust valve 16, and a single scavenge exhaust valve 18. In other embodiments, the blowdown exhaust ports 20, the scavenge exhaust port 22, or both, may converge toward each other into a single and common port(s) before exiting the body of the cylinder head 24. An example of exhaust ports that converge toward one another is disclosed in the International Application No. PCT/US11/21846 with an international filing date of Jan. 20, 2011, titled Directly Communicated Turbocharger, and in the name of applicant BorgWarner Inc. The International Application No. PCT/US11/21846 also discloses embodiments of a cylinder head and an internal combustion cylinder breathing system that may have application with the embodiments of the internal combustion engine valvetrain 10 of the present disclosure.

Downstream of the blowdown and scavenge exhaust ports 20, 22, an internal combustion engine breathing system may include, among other components, a pair of turbochargers, an exhaust gas after treatment device, one or more exhaust gas recirculation (EGR) subsystems or assemblies, and a charge-air cooler. One example of an internal combustion engine breathing system is disclosed in the International Application No. PCT/US11/21846; another example of an internal combustion engine breathing system is disclosed in the International Publication No. WO2009/105463 with an international filing date of Feb. 18, 2009, titled Controlling Exhaust Gas Flow Divided Between Turbocharging and Exhaust Gas Recirculating, and in the name of BorgWarner Inc., and the embodiments disclosed therein may be utilized with embodiments disclosed herein.

FIGS. 2-6 schematically show several embodiments of the internal combustion engine valvetrain 10. In all of the embodiments shown in FIGS. 2-6, the blowdown exhaust valves 16 and the scavenge exhaust valves 18 are independently operated and controlled via separate and distinct valve actuation mechanisms. The figures are schematic and are not necessarily meant to show specific arrangements and constructions of the valves and the valve actuation mechanisms—for example, the exact locations of the valves in application with respect to one another may be different than what is shown in FIGS. 2-6. The valve actuation mechanisms separately and distinctly open and close the blowdown exhaust valves 16 and the scavenge exhaust valves 18 independent of one another. In some embodiments, this may mean that the blowdown exhaust valves 16 and the scavenge exhaust valves 18 do not derive their opening and closing movements via a single and the same camshaft. This may also mean that one camshaft physically causes the opening and closing of the blowdown exhaust valve and not the scavenge exhaust valve, and another camshaft physically causes the opening and closing of the scavenge exhaust valve and not the blowdown exhaust valve. In some cases, providing separate and distinct opening and closing functionality of the blowdown exhaust valves 16 and the scavenge exhaust valves 18 may provide versatile engine operation which may facilitate optimization of engine performance including, for example, increased engine power and improved engine efficiency.

In the embodiment of FIG. 2, the intake valve 14, the blowdown exhaust valve 16, and the scavenge exhaust valve 18 may include a poppet valve 30 that may reciprocate linearly up-and-down in a combustion chamber 32 against and with the biasing force of a spring 34. Other constructions, arrangements, and components of the valves are possible. A first valve actuation mechanism 36 may be constructed and arranged to open and close both the intake valve 14 and the blowdown exhaust valve 16, and a second valve actuation mechanism 38 may be constructed and arranged to open and close the scavenge exhaust valve 18 separately, distinctly, and independently of the intake and blowdown exhaust valves. The first valve actuation mechanism 36 may be what-is-known-as a type three, and may include a first camshaft 40 having numerous lobes 42, and may also include a first rocker arm 44 and a second rocker arm 46. In use, the first camshaft 40 may rotate and spin while the lobes 42 impinge upon the first and second rocker arms 44, 46 which may then themselves move about their respective pivot and impinge upon the poppet valves 30 of the intake and blowdown exhaust valves 14, 16. In response, the poppet valves 30 may be opened and closed. Different lobes 42 may impinge upon the first and second rocker arms 44, 46 at different degrees of angular rotation of the first camshaft 40, which may cause the intake and blowdown exhaust valves 14, 16 to actuate at different times, and may cause the intake and blowdown exhaust valves to have different characteristics with respect to each other such as different timing and lift.

Furthermore, the second valve actuation mechanism 38 may be what-is-known-as a type one, and may include a second camshaft 48 having numerous lobes 50. In use, the second camshaft 48 may rotate and spin while the lobes 50 may directly impinge upon the poppet valve 30 of the scavenge exhaust valve 18, which may cause the poppet valve of the scavenge exhaust valve to open and close.

Still referring to the embodiment of FIG. 2, a variable valve timing mechanism 52 may be operatively equipped to the second camshaft 48 in order to continuously control actuation of the scavenge exhaust valve 18. In one embodiment, the variable valve timing mechanism 52 may be a variable camshaft phaser that may control event-phasing. Event phasing describes a way of advancing or retarding a valve's actuation phase (measured in crank angle degrees, from when a valve opens to when it closes) with respect to a piston stroke relative to a top-dead-center position. Operation of the variable valve timing mechanism 52 may be commanded from an associated engine control unit or module. And in one embodiment, the variable valve timing mechanism 52 may include, among other components, a variable force solenoid and a spool valve. In other embodiments, the variable valve timing mechanism may be of different types; may have different constructions; may have more, less, and/or different components; and may have different arrangements. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the first camshaft 40 in order to continuously control actuation of the intake and blowdown exhaust valves 14, 16. In one embodiment, the variable valve timing mechanism for the first camshaft 40 may be a variable camshaft phaser as described immediately above.

In the embodiments described above, the blowdown exhaust valve 16, the scavenge exhaust valve 18, or both, may be controlled—phases advanced, retarded, or both—according to the method disclosed in the International Publication No. WO2009/105463 which is described below with select portions taken from the '463 Publication. For example, when the second camshaft 48 is equipped with the variable valve timing mechanism 52 and the first camshaft 40 is not equipped with a variable valve timing mechanism, the control method of the International Publication No. WO2009/105463 may be used to control actuation of the scavenge exhaust valve 18 according to one illustrative embodiment. Using that control method, or using another suitable control method, exhaust gas may be delivered to the associated turbochargers in a selective way to control turbocharger boost; in some embodiments, a turbine bypass for the turbochargers may be eliminated. Also, using that control method, or using another suitable control method, exhaust gas may be delivered to the associated EGR subsystem in a selective way to improve engine operation. In one example, when both the first camshaft 40 and the second camshaft 48 are equipped with a variable valve timing mechanism such as the variable valve timing mechanisms described above, the valves 14, 16, 18 may be controlled in order to optimize engine power at heavy-load engine operation conditions and in order to optimize engine efficiency at light-to-moderate-load engine operating conditions. In this example, the control method may include one or more of the following instructions: i) at light-to-moderate load and lower speed, advance the phasing of the intake valves 14 and of the blowdown exhaust valves 16 in order to optimize engine power; ii) at heavy-load and high speed, retard the phasing of the intake valves 14 and of the blowdown exhaust valves 16 in order to optimize engine power; and iii) at light load and low speed, retard the phasing of the intake valves 14 and the blowdown exhaust valves 16 in order to optimize engine efficiency including fuel consumption efficiency.

In the embodiment of FIG. 3, a first valve actuation mechanism 54 may be constructed and arranged to open and close both the intake valve 14 and the blowdown exhaust valve 16, and a second valve actuation mechanism 56 may be constructed and arranged to open and close the scavenge exhaust valve 18 separately, distinctly, and independently of the intake and blowdown exhaust valves. The first valve actuation mechanism 54 may be what-is-known-as a type three, and may include a first camshaft 58 having numerous lobes 60, and may also include a first rocker arm 62 and a second rocker arm 64. General use and functionality of this type of valve actuation mechanism has been previously described. Likewise, the second valve actuation mechanism 56 may be what-is-known-as a type three, and may include a second camshaft 66 having numerous lobes 68, and may also include a third rocker arm 70. Again, general use and functionality of this type of valve actuation mechanism has been previously described. Still referring to FIG. 3, a variable valve timing mechanism 72 may be operatively equipped to the second camshaft 66 in order to continuously control actuation of the scavenge exhaust valve 18. In one embodiment, the variable valve timing mechanism 72 may be a variable camshaft phaser, as previously described. In other embodiments, the variable valve timing mechanism may be of different types; may have different constructions; may have more, less, and/or different components; and may have different arrangements. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the first camshaft 58 in order to continuously control actuation of the intake and blowdown exhaust valves 14, 16. In one embodiment, the variable valve timing mechanism for the first camshaft 58 may be a variable camshaft phaser, as previously described. Also, in the embodiment of FIG. 3, the variable valve timing mechanisms may be controlled according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

In the embodiment of FIG. 4, a first valve actuation mechanism 74 may be constructed and arranged to open and close both the intake valve 14 and the blowdown exhaust valve 16, and a second valve actuation mechanism 76 may be constructed and arranged to open and close the scavenge exhaust valves 18 separately, distinctly, and independently of the intake and blowdown exhaust valves. The first valve actuation mechanism 74 may be what-is-known-as a type two, and may include a first camshaft 78 having numerous lobes 80, and may also include a first rocker arm 82 and a second rocker arm 84. In use, the first camshaft 78 may rotate and spin while the lobes 80 impinge upon the first and second rocker arms 82, 84 which may then themselves move about their respective pivot and impinge upon the poppet valves 30 of the intake and blowdown exhaust valves 14, 16. Likewise, the second valve actuation mechanism 76 may be what-is-known-as a type two, and may include a second camshaft 86 having numerous lobes 88, and may also include a third rocker arm 90. General use and functionality of this type of valve actuation mechanism has been previously described. Still referring to FIG. 4, a variable valve timing mechanism 92 may be operatively equipped to the second camshaft 86 in order to continuously control actuation of the scavenge exhaust valve 18. In one embodiment, the variable valve timing mechanism 92 may be a variable camshaft phaser, as previously described. In other embodiments, the variable valve timing mechanism may be of different types; may have different constructions; may have more, less, and/or different components; and may have different arrangements. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the first camshaft 78 in order to continuously control actuation of the intake and blowdown exhaust valves 14, 16. In one embodiment, the variable valve timing mechanism for the first camshaft 78 may be a variable camshaft phaser, as previously described. Also, in the embodiment of FIG. 4, the variable valve timing mechanisms may be controlled according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

In the embodiment of FIG. 5, a first valve actuation mechanism 94 may be constructed and arranged to open and close the intake valve 14, a second valve actuation mechanism 96 may be constructed and arranged to open and close the blowdown exhaust valve 16, and a third valve actuation mechanism 98 may be constructed and arranged to open and close the scavenge exhaust valve 18. The first, second, and third valve actuation mechanisms 94, 96, 98 may actuate their respective valve separately, distinctly, and independently of the other two valves. The first valve actuation mechanism 94 may be what-is-known-as a type two, and may include a first camshaft 100 having numerous lobes 102, and may also include a first rocker arm 104. General use and functionality of this type of valve actuation mechanism has been previously described. Likewise, the second valve actuation mechanism 96 may be what-is-known-as a type two, and may include a second camshaft 106 having numerous lobes 108, and may also include a second rocker arm 110. General use and functionality of this type of valve actuation mechanism has been previously described. And similarly, the third valve actuation mechanism 98 may be what-is-known-as a type two, and may include a third camshaft 112 having numerous lobes 114, and may also include a third rocker arm 116. General use and functionality of this type of valve actuation mechanism has been previously described.

Still referring to FIG. 5, a variable valve timing mechanism 118 may be operatively equipped to the third camshaft 112 in order to continuously control actuation of the scavenge exhaust valve 18. In one embodiment, the variable valve timing mechanism 118 may be a variable camshaft phaser, as previously described. In other embodiments, the variable valve timing mechanism may be of different types; may have different constructions; may have more, less, and/or different components; and may have different arrangements. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the first camshaft 100 in order to continuously control actuation of the intake valve 14. In one embodiment, the variable valve timing mechanism for the first camshaft 100 may be a variable camshaft phaser, as previously described. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the second camshaft 106 in order to continuously control actuation of the blowdown exhaust valve 16. In one embodiment, the variable valve timing mechanism for the second camshaft 106 may be a variable camshaft phaser, as previously described. Also, in the embodiment of FIG. 5, the variable valve timing mechanisms may be controlled according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

In the embodiment of FIG. 6, a first valve actuation mechanism 120 may be constructed and arranged to open and close the intake valve 14, a second valve actuation mechanism 122 may be constructed and arranged to open and close the blowdown exhaust valve 16, and a third valve actuation mechanism 124 may be constructed and arranged to open and close the scavenge exhaust valve 18. The first, second, and third valve actuation mechanisms 120, 122, 124 may actuate their respective valve separately, distinctly, and independently of the other two valves. The first valve actuation mechanism 120 may be what-is-known-as a type one, and may include a first camshaft 126 having numerous lobes 128. General use and functionality of this type of valve actuation mechanism has been previously described. The second valve actuation mechanism 122, on the other hand, may be what-is-known-as a type two, and may include a second camshaft 130 having numerous lobes 132, and may also include a second rocker arm 134. General use and functionality of this type of valve actuation mechanism has been previously described. And similarly, the third valve actuation mechanism 124 may be what-is-known-as a type two, and may include a third camshaft 136 having numerous lobes 138, and may also include a third rocker arm 140. General use and functionality of this type of valve actuation mechanism has been previously described.

Still referring to FIG. 6, a variable valve timing mechanism 142 may be operatively equipped to the third camshaft 136 in order to continuously control actuation of the scavenge exhaust valve 18. In one embodiment, the variable valve timing mechanism 142 may be a variable camshaft phaser, as previously described. In other embodiments, the variable valve timing mechanism may be of different types; may have different constructions; may have more, less, and/or different components; and may have different arrangements. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the first camshaft 126 in order to continuously control actuation of the intake valve 14. In one embodiment, the variable valve timing mechanism for the first camshaft 126 may be a variable camshaft phaser, as previously described. Furthermore, though not shown, a separate and distinct variable valve timing mechanism may be operatively equipped to the second camshaft 130 in order to continuously control actuation of the blowdown exhaust valve 16. In one embodiment, the variable valve timing mechanism for the second camshaft 130 may be a variable camshaft phaser, as previously described. Also, in the embodiment of FIG. 6, the variable valve timing mechanisms may be controlled according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

The internal combustion engine valvetrain 10 may have other embodiments that are not shown in the figures. For example, in one embodiment, a first valve actuation mechanism may be constructed and arranged to open and close both the intake valve and the blowdown exhaust valve, and a second valve actuation mechanism may be constructed and arranged to open and close the scavenge exhaust valve separately, distinctly, and independently of the intake and blowdown exhaust valves. The first valve actuation mechanism may be what-is-known-as a type three, as previously described; and the second valve actuation mechanism may be what-is-known-as a type two, as previously described. In this embodiment, the second valve actuation mechanism may be equipped with variable valve timing functionality such as a variable camshaft phaser, as previously described. Further, the first valve actuation mechanism may be equipped with variable valve timing functionality such as a variable camshaft phaser, as previously described. And, in this embodiment, the variable valve timing functionality may be according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

In another embodiment not shown in the figures, a first valve actuation mechanism may be a first camless valve actuation mechanism and may be constructed and arranged to open and close the intake valve, and a second valve actuation mechanism may be a second camless valve actuation mechanism and may be constructed and arranged to open and close the scavenge exhaust valve. In an example camless valve actuation mechanism, individual actuators may be equipped at each individual poppet valve, and may be electromagnetically controlled, hydraulically controlled, pneumatically controlled, a combination thereof, or controlled another way. In this embodiment, a third valve actuation mechanism may be constructed and arranged to open and close the blowdown exhaust valve. The third valve actuation mechanism may include a camshaft having numerous lobes, and may be what-is-known-as a type one, type two, or type three, as all previously described. The first, second, and third valve actuation mechanisms may actuate their respective valve separately, distinctly, and independently of the other two valves. Further, in this embodiment, the third valve actuation mechanism may be equipped with variable valve timing functionality such as a variable camshaft phaser, as previously described. The variable valve timing functionality may be according to the methodology described in relation to the embodiment of FIG. 2, including the method disclosed in the International Publication No. WO2009/105463.

Still in other embodiments not shown in the figures, the valve actuation mechanisms of the embodiments shown in FIGS. 2-6 may instead be constructed and arranged to constitute what-is-known-as a type four. For example, in the embodiment of FIG. 5, the first valve actuation mechanism 94 may be a type four, and may include a camshaft having numerous lobes, a rocker arm, and a lifter; in other examples, the type four may include other components and/or different components.

In further embodiments not shown in the figures, embodiments similar to those shown in FIGS. 2-4 with two camshafts that are separate and distinct from one another may include valve actuation mechanisms of any combination of the what-are-known-as types one, two, three, and four. For example, one embodiment may include a type one and a type two; another embodiment may include a type three and a type four; another embodiment may include a type two and a type four; and other examples exist. In further embodiments not shown in the figures, embodiments similar to those shown in FIGS. 5 and 6 with three camshafts that are separate and distinct from one another may include valve actuation mechanisms of any combination of the what-are-known-as types one, two, three, and four. For example, one embodiment may include a first type three, a second type three, and a type two; another embodiment may include a type one, a type three, and a type four; another embodiment may include a first type one, a second type one, and a type three; and other examples exist.

In other embodiments, the valve actuation mechanisms of the embodiments shown in FIGS. 1-6 and other embodiments not shown may be operatively equipped with variable valve timing functionality such as what-is-commonly called multiair variable valve timing, or what-is-commonly called uniair variable valve timing. Referring to FIG. 7, in one example, a camshaft 144 having numerous lobes 146 may impinge upon a cam follower 148 such as a roller rocker arm or a piston. The cam follower 148 may communicate with an oil chamber 150 which may cause a hydraulic valve actuation mechanism 152 to open and close the respective poppet valve 30. A solenoid valve 154, which may be commanded via an associated engine control unit or module, may interact with the oil chamber 150 in order to vary valve timing and lift. In other examples, these variable valve timing functionalities may include more, less, or different components than shown and described here.

The control method of the International Publication No. WO2009/105463 referred to above will now be described with reference to FIGS. 8-14, and with select portions taken from the '463 Publication. In general, optimal valve timing of blowdown and scavenging valves will be application specific and, thus, will vary from engine to engine. But the blowdown valves may have relatively advanced timing, have longer valve opening duration, with higher lift than the scavenging valves. In one example, the lift of the blowdown valves may be the maximum lift attainable in approximately 180 degrees of crank angle, and the lift of the scavenging valves may be the maximum lift attainable in approximately 160 degrees of crank angle.

Example valve timing including duration and/or lift for the blowdown valve(s) may be on the order of about 70 to 100% of valve timing for the same or similar engine equipped with conventional exhaust valves. More specific exemplary valve timing for the blowdown valve(s) 24 may be about 85-95% (e.g. 90%) duration and about 90-100% (e.g. 95%) lift of valve duration and lift timing for the same or similar engine equipped with conventional exhaust valves. Valve opening timing of the blowdown valve(s) generally may be similar to or retarded at minimum turbocharger boost condition, and advanced to increase boost. Example phase authority for the blowdown valve(s) may be on the order of about 25 to 40 degrees (e.g. 28 degrees) of crankshaft angle between about 2000 and 5500 RPM.

Example valve timing including duration and/or lift for the scavenging valve(s) may be on the order of about 60 to 90% of valve timing for the same or similar engine equipped with conventional exhaust valves. More specific exemplary valve timing for the scavenging valve(s) may be about 75-85% (e.g. 80%) duration and about 80-90% (e.g. 85%) lift of valve duration and lift timing for the same or similar engine equipped with conventional exhaust valves. Valve closing timing of the scavenging valve(s) generally may be similar to valve closing timing of the same or similar engine equipped with conventional exhaust valves. Example phase authority for the scavenging valve(s) may be on the order of about 30 to 60 degrees (e.g. 40 degrees) of crankshaft angle between about 2000 and 5500 RPM.

Referring now to FIG. 8, an example method 300 is illustrated in flow chart form. As the description of the method 300 progresses, reference will be made to the timing diagrams of FIGS. 9 through 14. As shown at step 305, the method 300 may be initiated in any suitable manner. For example, the method 300 may be initiated at startup of the ICE 12. At step 310, fresh air may be drawn into an induction subsystem of an engine system, and induction gases may be inducted into an engine of the engine system through the induction subsystem. At step 315, exhaust gases may be exhausted from an engine through an exhaust subsystem of an engine system. For example, exhaust gases may be exhausted from the ICE 12 through the associated exhaust manifold(s). The exhaust valves 16, 18 may be actuated independently of each other to apportion exhaust gas flow between turbocharger(s) and the EGR subsystem(s).

At step 320, when an engine is running at or near idle speed(s) and at low or no load, exhaust valves may be controlled to reduce or minimize internal residual gases. In one example, and referring also to FIG. 9, the opening of the blowdown and scavenging exhaust valves 16, 18 may be controlled for increased or maximal overlap. In a more specific example, one or more of the blowdown exhaust valves 16 may be fully retarded 24 a and one or more of the scavenging valves 18 may be fully advanced 25 a. According to a particular example, at least one of the blowdown exhaust valves 16 may be retarded by about 10 to 20 degrees and at least one of the scavenging exhaust valves 18 may be advanced by about 20 to 30 degrees. As shown in FIG. 9, at least one of the blowdown exhaust valves 16 may be retarded such that the valve(s) start(s) to open just before BDC such as within about 0 to 45 (e.g. 15 to 25) degrees before BDC, and at least one of the scavenging exhaust valves 18 may be advanced such that the valve(s) start(s) to close just after TDC such as within about 10 to 45 (e.g. 15 to 20) degrees after TDC.

At step 325, when high load or maximum transient response is demanded from an engine, such as an engine running at or near idle speed(s) and at no or low load, exhaust valves may be controlled to increase or maximize energy delivery to a turbocharger turbine. In one example, and referring to FIG. 10, the opening of the blowdown and scavenging exhaust valves 16, 18 may be controlled for minimal overlap. In a more specific example, one or more of the blowdown exhaust valves 16 may be fully advanced and one or more of the scavenging valves 18 may be fully retarded. According to a particular example, at least one of the blowdown exhaust valves 16 may be advanced by about 10 to 40 (e.g. 15 to 20) degrees and at least one of the scavenging exhaust valves 18 may be retarded by about 20 to 60 (e.g. 25 to 30) degrees. As shown in FIG. 10, at least one of the blowdown exhaust valves 16 may be advanced such that the opening of the valve(s) is/are well before BDC such as within 40 to 50 degrees before BDC, and at least one of the scavenging exhaust valves 18 may be retarded such that the closing of the valve(s) is/are well after TDC such as within about 45 to 80 (e.g. 50 to 60) degrees after TDC.

At step 330, when an engine is running substantially at intermediate speed(s) and/or load(s), and where little to no engine load demand (i.e. turbocharger boost) is desired or required, exhaust valves may be controlled to compromise or provide a desired or required balance between desired internal residual gas fraction (or internal EGR) and turbocharger speed. In one example, and referring also to FIG. 11, the timing of the blowdown and scavenging exhaust valves 16, 18 may be controlled for variable overlap in valve timing. In a more specific example, one or more of the blowdown exhaust valves 16 may be positioned optimally for best engine efficiency, and one or more of the scavenging valves 18 may be variably advanced or retarded to the fully advanced 25 a or fully retarded 25 b positions or anywhere in between to achieve a desirable balance between internal EGR and turbocharger speed. In one particular instance, one or more of the blowdown exhaust valves 16 may be unidirectionally or fully retarded 24 a. According to a particular example, at least one of the blowdown exhaust valves 16 may be retarded by about 10 to 20 degrees and at least one of the scavenging exhaust valves 18 may be advanced or retarded about 20 to 30 degrees within an overall range of about 40 to 60 degrees. At least one of the blowdown exhaust valves 16 may be retarded such that the valve(s) start(s) to open just before BDC such as within about 15 to 25 degrees before BDC. At least one of the scavenging exhaust valves 18 may be varied between an advanced limit such that the valve(s) start(s) to close within 0 to 10 degrees after TDC and a retarded limit such that the valve(s) start(s) to close within 50 to 60 degrees after TDC.

At step 335, when an engine is running substantially at intermediate speed(s) and/or load(s) where at least some turbocharger boost is desired or required, exhaust valves may be variably controlled for good engine efficiency. Referring to FIG. 12, in one example according to multi-step variable control, first, one or more of the scavenging valves 18 may be retarded to increase blowdown exhaust energy for boost and, substantially simultaneously, TDC overlap of the scavenging valve(s) 18 and the intake valve(s) 14 may be increased to increase internal EGR. The TDC overlap may be achieved, for example, by at least maintaining the timing of the intake valve(s) 14 or advancing the intake valves(s) 14. Second, when a desired or required internal EGR level is achieved, one or more of the blowdown valve(s) 16 may be advanced for additional boost. According to a particular example, at least one of the scavenging exhaust valves 18 may be retarded by 20 to 30 degrees while at least one of the intake valves 14 is held steady or advanced by 5 to 30 degrees. Then, at least one of the blowdown exhaust valves 16 may be advanced within a range of about 10 to 20 degrees. At least one of the scavenging exhaust valves 18 may be retarded such that the valve(s) start(s) to open within about 50 to 60 degrees after TDC, and at least one of the intake valves 14 may be maintained or advanced such that the valve(s) 14 start to open within about 30 degrees before TDC to about 30 degrees after TDC. At least one of the blowdown exhaust valves 16 may be advanced such that the valve(s) start(s) to open within about 40 to 50 degrees before BDC. In another example, according to step 335, and referring to FIG. 13, one or more of the blowdown valve(s) 16 may be variably controlled substantially simultaneously with the variable control of the scavenging exhaust valve(s) 18 and the advancing of the intake valve(s) 14 for a good balance of boost and engine efficiency regardless of when or if a particular internal EGR level is achieved.

At step 340, when an engine is running substantially at high or maximum speed(s) and/or load(s), exhaust valves may be controlled, for example, to protect one or more turbochargers. In one example, and referring also to FIG. 14, the opening of the blowdown and scavenging exhaust valves 16, 18 may be controlled for increased overlap similar to that of FIG. 9 but perhaps to a lesser degree and for variable overlap similar to that of FIG. 11 but reversed. In a more specific example, one or more of the scavenging exhaust valves 18 may be substantially if not fully advanced and one or more of the blowdown valves 16 may be variably advanced or retarded to modulate turbocharger boost level, for example, and to minimize PMEP. According to a particular example, at least one of the scavenging exhaust valves 18 may be advanced by about 20 to 30 degrees and at least one of the blowdown exhaust valves 16 may be advanced or retarded within a range of about 10 to 20 degrees within an overall range of about 20 to 40 degrees. As shown in FIG. 14, at least one of the scavenging exhaust valves 18 may be advanced such that the valve(s) start(s) to close just after TDC such as within about 15 to 25 degrees after TDC. As also shown in FIG. 14, at least one of the blowdown exhaust valves 16 may be varied between an advanced limit such that the valve(s) start(s) to open within about 40 to 50 degrees before BDC and a retarded limit such that the valve(s) start(s) to open within about 15 to 25 degrees before BDC. An example overall strategy for full load may be to phase both blowdown and scavenging cams to optimize engine efficiency at a target boost level.

At step 345, exhaust gases may be recirculated from an exhaust subsystem through one or both of high and/or low pressure EGR paths to an induction subsystem of an engine system. At step 346, as a default, scavenging exhaust gases may be prioritized over blowdown exhaust gases for EGR for recirculation of relatively cooler scavenging exhaust gases. In other words, more scavenging exhaust gas than blowdown exhaust gas may be apportioned through an EGR subsystem. For example, as a default, EGR may be carried out using 100% scavenging exhaust gases. At step 347, according to one or more exceptions to the default of step 346, EGR may be supplemented with at least some blowdown EGR. One example exception includes engine warm up after a cold start to quickly raise engine and/or catalytic converter temperature. Another exemplary exception includes situations in which a pressure drop across an engine is insufficient to provide a desired or required EGR rate from scavenging exhaust gases alone.

At step 348, EGR may be provided entirely by blowdown exhaust gases, such as to prevent reverse exhaust gas flow from a blowdown exhaust manifold to a scavenging exhaust manifold. In such a case, the scavenging gases may be entirely blocked from EGR. At step 349, EGR instead or also may be provided by LP EGR. At step 350, energy from exhaust gases may be extracted and converted to energy to compress induction gases. At step 351, boost levels of a VTG turbocharger may be controlled. At step 352, multiple turbochargers may be driven by a blowdown manifold.

In a first mode, at step 353, for example, with high or maximum turbocharger demand at relatively low engine speeds and loads such as at engine idle, the exhaust valves 16, 18 may be controlled as set forth in step 325, and a first turbocharger may perform most and perhaps all of the turbocharging while a second turbocharger may perform little to none of the turbocharging. In this first mode, most if not all of the energy from the exhaust gas flowing from a blowdown exhaust manifold is used to run a first turbine and, thus, compress air in a first compressor. In a second mode, at step 354, for example, at relatively high or maximum engine speeds and loads, the exhaust valves 16, 18 may be controlled as set forth in step 340, and a second turbocharger may perform most if not all of the turbocharging while a first turbocharger may perform little to none of the turbocharging.

In a third mode, at step 355, for example, at relatively medium engine speeds and loads, control of the exhaust valves 16, 18 may be modulated and turbocharging may be modulated between first and second turbochargers to achieve relatively low PMEP levels. Finally, at step 360 the method 300 may be suspended in any suitable manner. For example, the method 300 may be suspended at shutdown of the ICE 12.

The following is a description of select illustrative embodiments within the scope of the invention. The invention is not, however, limited to this description; and each embodiment and components, elements, and steps within each embodiment may be used alone or in combination with any of the other embodiments and components, elements, and steps within the other embodiments.

Embodiment one may include an internal combustion engine valvetrain for an internal combustion engine. The internal combustion engine may include one or more cylinders which may have one or more intake valves, one or more blowdown exhaust valves, and one or more scavenge exhaust valves. The internal combustion engine valvetrain may include a first valve actuation mechanism that may be constructed and arranged to actuate the one or more blowdown exhaust valves. The internal combustion engine valvetrain may also include a second valve actuation mechanism that may be constructed and arranged to actuate the one or more scavenge exhaust valves. The first valve actuation mechanism may be a separate and distinct component than the second valve actuation mechanism.

Embodiment two, which may be combined with embodiment one, may further describe the first valve actuation mechanism as including a camshaft and a rocker arm that may be constructed and arranged to actuate the one or more blowdown exhaust valves, and that may be constructed and arranged to actuate the one or more intake valves.

Embodiment three, which may be combined with any one of embodiments one to two, may further describe the second valve actuation mechanism as including a second camshaft that may be constructed and arranged to actuate the one or more scavenge exhaust valves. The internal combustion engine valvetrain may further include a variable valve timing mechanism that may be operatively equipped to the second camshaft.

Embodiment four, which may be combined with any one of the embodiments one to three, may further describe the variable valve timing mechanism as including a variable camshaft phaser.

Embodiment five, which may be combined with any one of the embodiments one to four, may describe the internal combustion engine valvetrain as further including a second variable valve timing mechanism that may be operatively equipped to the first camshaft.

Embodiment six, which may be combined with any one of the embodiments one to five, may describe the first valve actuation mechanism as including a first camshaft. The second valve actuation mechanism may include a second camshaft. And the internal combustion engine valvetrain may include a third valve actuation mechanism which may have a third camshaft that may be constructed and arranged to actuate the one or more intake valves.

Embodiment seven, which may be combined with any one of the embodiments one to six, may further describe the first valve actuation mechanism as including a camshaft. The second valve actuation mechanism may include a first camless valve actuation mechanism. The internal combustion engine valvetrain may include a second camless valve actuation mechanism that may be constructed and arranged to actuate the one or more intake valves.

Embodiment eight, which may be combined with any one of the embodiments one to seven, may further describe the first valve actuation mechanism as including a first camshaft. The second valve actuation mechanism may actuate the one or more intake valves. The second valve actuation mechanism may include a second camshaft. The internal combustion engine valvetrain may include a variable valve timing mechanism that may be operatively equipped to the second camshaft. The variable valve timing mechanism may include an oil chamber and a solenoid valve that may selectively interact with the oil chamber during valve actuation.

Embodiment nine may include an internal combustion engine valvetrain for an internal combustion engine. The internal combustion engine may include one or more cylinders which may have one or more intake valves, one or more blowdown exhaust valves, and one or more scavenge exhaust valves. The internal combustion engine valvetrain may include a first actuation means that may be constructed and arranged to actuate the one or more blowdown exhaust valves, and that may be constructed and arranged to actuate the one or more intake valves. The internal combustion engine valvetrain may include a second actuation means that may be constructed and arranged to actuate the one or more scavenge exhaust valves.

Embodiment ten, which may be combined with embodiment nine, may further describe the internal combustion engine valvetrain as including a variable camshaft phaser that may be operatively equipped to the second actuation means.

Embodiment eleven, which may be combined with any one of the embodiments nine to ten, may further describe the first actuation means as including a first camshaft and a first rocker arm. The second actuation means may include a second camshaft.

Embodiment twelve may include actuating a blowdown exhaust valve of an internal combustion engine, and may include, separately and distinctly, actuating a scavenge exhaust valve of the internal combustion engine.

Embodiment thirteen, which may be combined with embodiment twelve, may further describe actuating the blowdown exhaust valve of the internal combustion engine by way of a first valve actuation mechanism. The embodiment may also further describe actuating the scavenge exhaust valve of the internal combustion engine by way of a second valve actuation mechanism that may be a separate and distinct component than the first valve actuation mechanism.

Embodiment fourteen, which may be combined with any one of the embodiments twelve to thirteen, may include actuating an intake valve of the internal combustion engine by way of the first valve actuation mechanism.

The above description of embodiments of the invention is merely illustrative in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the invention. 

What is claimed is:
 1. A product comprising: an internal combustion engine valvetrain for an internal combustion engine with at least one cylinder having at least one intake valve, at least one blowdown exhaust valve, and at least one scavenge exhaust valve, the internal combustion engine valvetrain comprising a first valve actuation mechanism constructed and arranged to actuate the at least one blowdown exhaust valve, and including a second valve actuation mechanism constructed and arranged to actuate the at least one scavenge exhaust valve, wherein the first valve actuation mechanism is a separate and distinct component than the second valve actuation mechanism.
 2. A product as set forth in claim 1 wherein the first valve actuation mechanism comprises a camshaft and a rocker arm that are constructed and arranged to actuate the at least one blowdown exhaust valve and that are constructed and arranged to actuate the at least one intake valve.
 3. A product as set forth in claim 2 wherein the second valve actuation mechanism comprises a second camshaft that is constructed and arranged to actuate the at least one scavenge exhaust valve, and wherein the internal combustion engine valvetrain further comprises a variable valve timing mechanism operatively equipped to the second camshaft.
 4. A product as set forth in claim 3 wherein the variable valve timing mechanism comprises a variable camshaft phaser.
 5. A product as set forth in claim 4 wherein the internal combustion engine valvetrain further comprises a second variable valve timing mechanism operatively equipped to the first camshaft.
 6. A product as set forth in claim 1 wherein the first valve actuation mechanism comprises a first camshaft, and the second valve actuation mechanism comprises a second camshaft, and wherein the internal combustion engine valvetrain further comprises a third valve actuation mechanism with a third camshaft constructed and arranged to actuate the at least one intake valve.
 7. A product as set forth in claim 1 wherein the first valve actuation mechanism comprises a camshaft, and the second valve actuation mechanism comprises a first camless valve actuation mechanism, and wherein the internal combustion engine valvetrain further comprises a second camless valve actuation mechanism that is constructed and arranged to actuate the at least one intake valve.
 8. A product as set forth in claim 1 wherein the first valve actuation mechanism comprises a first camshaft, wherein the second valve actuation mechanism also actuates the at least one intake valve, wherein the second valve actuation mechanism comprises a second camshaft, and wherein the internal combustion engine valvetrain further comprises a variable valve timing mechanism operatively equipped to the second camshaft, the variable valve timing mechanism comprising an oil chamber and a solenoid valve that selectively interacts with the oil chamber during valve actuation.
 9. A product comprising: an internal combustion engine valvetrain for an internal combustion engine with at least one cylinder having at least one intake valve, at least one blowdown exhaust valve, and at least one scavenge exhaust valve, the internal combustion engine valvetrain comprising a first actuation means constructed and arranged to actuate the at least one blowdown exhaust valve and constructed and arranged to actuate the at least one intake valve, the internal combustion engine valvetrain comprising a second actuation means constructed and arranged to actuate the at least one scavenge exhaust valve.
 10. A product as set forth in claim 9 wherein the internal combustion engine valvetrain comprises a variable camshaft phaser operatively equipped to the second actuation means.
 11. A product as set forth in claim 10 wherein the first actuation means comprises a first camshaft and a first rocker arm, and wherein the second actuation means comprises a second camshaft.
 12. A method comprising: actuating a blowdown exhaust valve of an internal combustion engine; and separately and distinctly, actuating a scavenge exhaust valve of the internal combustion engine.
 13. A method as set forth in claim 12 wherein actuating the blowdown exhaust valve further comprises actuating the blowdown exhaust valve of the internal combustion engine via a first valve actuation mechanism, and wherein actuating the scavenge exhaust valve further comprises actuating the scavenge exhaust valve of the internal combustion engine via a second valve actuation mechanism that is a separate and distinct component than the first valve actuation mechanism.
 14. A method as set forth in claim 13 further comprising: actuating an intake valve of the internal combustion engine via the first valve actuation mechanism. 